ReJJeEihns on PruJJiats^ J 



' A folutlon of cobalt furnifiies a greyifli violet, and, with 

 the addition of muriat of ammonia, a beautiful violet blue j 

 while, in treating folutions of the fulphat of zinc, the nitrat 

 of bifmuth, the muriat of tin, and the acetite of lead, with 

 liquor of the pruffiat of pot-a(h or of lime, acidulated as be- 

 fore, you obtain only whites. Copper is precipitated under 

 a brown (hade. The muriat of antimony, precipitated by 

 aqueous dilution, and expofed, like the oxyd of filver, to the 

 aftion of the acidulated prufliat of pot-aili, indicates fome 

 difpofition to become blue. Adding to the muriatic folution 

 of the black oxyd of manganefe, muriat of ammonia, and 

 mixing this folulion with liquor of the prufliat of pot-afh, 

 acidulated by the fulphuric acid, there is formed a very beau- 

 tiful blue. 



I muft inform chemifts'not to be difcouraged when the 

 produ(ftion of blue does not immediately take place j if it 

 {Iiould happen that they do not obtain it, they muft vary the 

 proportions until they have accompliflied their end. The 

 blue of filver often does not fucceed till after a long time, 

 and does not acquire its utuioft degree of intenfity till the 

 end of eight, ten, or fifteen days. 



As I intended to repeat and continue thefe experiments 

 by the mixture of metallic folutions with liquor of the pruf- 

 fiats of pot-a(h and lime acidulated, I firft expofed to the 

 aftion of thefe liquors, fome metallic oxyds fixed upon ftuffs. 

 Cotton cloth, which had imbibed a folution of native pla- 

 tina almoft infenfible to the magnet, after being wrung was 

 dipped, without drying it, in a folution of caulHc pot-afli ; 

 the oxyd of platina remained, in a great part, adhering to the 

 ftuff, which being wafhed, alfumed a yellow much more 

 beautiful than that obtained from iron. Having dipped this 

 cloth in a folution of prufliat of pot-afli or of lime, acidulated 

 by the fulphuric acid, I obtained as lively a blue, and in as 

 iliort a time as if I had employed cloth coloured by the 

 oxyd of iron. A mixture of the folution of platina and of 

 tin diflblved in the muriatic acid, with an excefs of acid, is 

 of a beautiful tranfparent red colour. Without exctfs of 

 acid, tliere is form<;d, at firft, a precipitate of a beautiful 



orange 



